TXX-6116, Summary of Analysis Used to Evaluate Habitability of Comanche Peak Steam Electric Station Control Room During Postulated Chlorine Release
| ML20211M013 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/30/1986 |
| From: | TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | |
| Shared Package | |
| ML20211L993 | List: |
| References | |
| TXX-6116, NUDOCS 8612160174 | |
| Download: ML20211M013 (23) | |
Text
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.TXX-6116 December 8, 1986 Page 1 of 16 TEXAS UTILITIES GENERATING COMPANY COMANCHE PEAK STEAM ELECTRIC STATION UNITS 1 AND 2
=
SUMMARY
OF THE ANALYSIS USED TO EVALUATE THE HABITABILITY OF THE CPSES CONTROL ROOM DURING A POSTULATED CHLORINE RELEASE NOVEMBER 1986 4
hk A
TXX-6116 December 8,1986 Page 2 of 16 TABLE OF CONTENTS SECTION TITLE
1.0 INTRODUCTION
2.0 EQUATIONS USED IN THE EVALUATION 2.1 Peak Outside Concentration as a Function of Distance from the Control Room 2.2 Methods Used to Calculate the Peak Concentration in the Control Room 2.2.1 High Windspeed Case 2.2.2 Low Windspeed Case 3.0 NUMERICAL CALCULATIONS 3.1 Release from the Circulating Water Chlorination Building (CWCB) 3.1.1 Peak Outside Concentration 3.1.2 control Room Chlorine Concentration 3.2 Release from the Service Water Chlorination Building (SWCB) 3,2.1 Peak Outside Concentration 3.2.2 Control Room Chlorine Concentration 4.0
.RESULTS
5.0 CONCLUSION
S
6.0 REFERENCES
L
TXX-6116 0:cember 8,1986 Page 3 of 16 LIST OF FIGURES FIGURE Eff 1
Topographic Mal, of the CPSES Site 2
Topographic Profile for the Release From the Circulating Water Chlorination Building 3
Topogr,aphic Profile for the Release From the Service Water Chlorination Building
3 TXX-6116 D:cemb:r,8, 1986 Page 4 of 16
1.0 INTRODUCTION
The concentrations of chlorine in the CPSES Control Room (CR) due to an accidental release of chlorine from a one-ton tank stored at the site were analyzed using the model described in Appendix B of NUREG/CR-3786 entitled, "A Review of Regulatory Requirements Governing Control Room Habitability Systems."
Chlorine tariks on site are located in the Circulating _ Water Chlorination Building (CWCB) and in the Service Water Chlorination Building (SWCB).
Therefore, both chlorination buildings were considered as source locations in the analysis.
An isolation air exchange rate of 810 cfm (an infiltration rate of 800 cfm and a 10 cfm allowance for ingress and egress) was assumed in the analysis.
The 800 cfm infiltration rate corresponds to the criterion used to test the pressurization of the Control Room at 1/8-inch water gage.
l TXX-6116 D:cember 8, 1986 Page 5 of 16
/
2.0 EQUATIONS USED IN THE EVALUATION 2.1 Peak Outside Concentration as a Function of Distance from the Control F.oom The peak outside concentration as a function of distance and quantity released is calculated using the lower of the X/Q from the following equations:
X/Q - 1/[6.28*(,2 +,2)* H]
(la)
H I
X/Q - 1/[7.87*( a2 +,2)*(,2 +,2)1/2]
(1b)
H I
v I
where X/Q - the unit concentration at coordinates x,y,z from the center of the puff (1/m3)
- horizontal standard deviation of the puff (m) a v - vertical standard deviation of the puff (m) a
- initial standard deviation of the puff (m) a Calculated according to the equation
- (Q1/(7.87*p))l/3 (2) a where Q1 - quantity instantaneously vaporized (g) p - density of the gas at standard conditions (g/m3)
H - CR air intake height (m) 2.2 Methods Used to Calculate the Peak Concentration in the Control Room 2.2.1 High Windspeed Case The first method considers a high windspeed case and assumes a linear buildup of external concentration from the detection level of 5 ppm to the peak concentration in a time period equal to the CR isolation time.
Under these assumptions, the peak concentration in the Control Room is given by:
i
TXX-6116 '
December 8, 1986 Page 6 of 16 XI-R1
- At
- Xo/7.2 (3) where X1 - CR concentration at isolation (ag/m3)
R1 - normal air exchange rate (hr-1)
At - isolation time (sec)
Xo - peak outside concentration (g/m3) 7.2 - combined coefficient and conversion factor for consistent units However, when it is assumed that chlorine detection of 5 ppa occurs at a distance of about 4.5 standard deviations from the puff center, the windspeed implied by equation (3) will exceed 7 m/s, thus making necessary a modification of equation (3).
Therefore, equation (3) is used to calculate the peak concentration in the CR, unless:
At/(0.64* a) < 1.0 (4) where a - ( a2 + o2)1/2 H
I in which case, equation (3) is modified to the following equation:
X[-(R1*At*Xo)/(4.7*a)
(5) 2 2.2.2 Low Windspeed Case The second method, based on lower windspeeds, also assumes a linear buildup of concentration i
from 5 ppm to the peak concentration, but in 2 minutes instead of the isolation time.
The equation to use is:
2 2 - ((R
- At )/432 + (17*R )/K]*Xo (6)
X 1
2 where X2 - CR concentration at isolation (mg/m3) 4 4
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TXX-6116 DGcember 8,1986 Page 7 of 16 R2 - isolated air exchange rate as evaluated for CR pressuri-zation of 1/8 inch water gage (hr-1)
K - buildup reduction factor (function of how R2 is determined and how much of the inleakage comes from internal control building zones)
The first term of this equation accounts for the CR concentration resulting from normal air intake prior to isolation, while the second term accounts for the contribution from inleakage following isolation.
For a K-factor of 8, equation (6) becomes:
2 2 - [(R1* At )/432 + (2.12*R ))*Xo (7)
X 2
Equation (7) is used to calculate the peak Control Room chlorine concentration for the low windspeed case.
If the Control Room chlorine concentration, calculated according to one of the equations mg/m3 [Eqs.
above (3), (5), or (7)], is less than 45 (15 ppm),
the CR is sufficiently leaktight.
F TXX-6116 D:cember 8,1986
-Page 8 of 16 3.0 NUMERICAL CALCUIATIONS 3.1 Release from the Circulating Water Chlorination Building (CWCB) 3.1.1 Peak Outside Concentration Distance between CWCB and CR: 245 m a - 9.3 m H
av - 4.8 m a - 2.08 m I
Calculated with Eq. (2) as follows:
Q1 - 2.268x105 g (0.25 tons) p - 3209 g/m3
- (2.268x10 /(7.87x3209))l/3 - 2.08 m 5
a IH - 17.38 m Applying Eq.
(la),
(X/Q)CWCB - 1.01x10-4 m-3 Applying Eq.
(1b),
(X/Q)CWCB - 2.67x10-4 m-3 The lower of the two X/Q's is the one calculated according to Eq. (la).
Therefore, (X/Q) - 1.01x10-4 m*3 is selected as the peak outside concentration.
3.1.2 Control Room Chlorine Concentration High Windspeed Case:
In order to select between Eq.
(3) and Eq.
(5), we test according to Eq. (4):
a - 9.53 m At - 10 see Thus, 10/(0.64x9.53) - 1,64 > 1
TXX-6116 Decemb:r 8,1986 Page 9 of 16 Therefore, Eq. (3) is used:
R1 - 4.25x10-1 hr-1, calculated as follows:
Normal air flow exchange rate: 3000 cfm Volume of the CR complex: 423032 ft3 then R1 - 3000x60/423032 - 4.25x10-1 hr*1 (Xo)CWCB - (1.01x10-4) x (2.268x10 )
5
- 22.91 g/m3 (X ) CWCB - 13.52 mg/m3 Applying Eq. (3):
1 1.ow Windspeed Case:
Eq. (7) is applicable:
R2 - 1.15x10-1 hr-1, calculated as follows:
Isolation air flow exchange rate: 810 cfm (800 cfm from infiltration and 10 cfm from opening and closing doors)
Volume of the CR complex: 423032 ft3 then R2 - 810 x 60/423032 - 1.15x10-1 hr-1 (X ) CWCB - 7.84 mg/m3 Applying Eq. (7):
2 3.2 Release from the Service Water Chlorination Building (SWCB) 3.2.1 Peak Outside Concentration Distance between SCWB and CR: 185.3 m a - 7.2 m H
av - 3.8 m a - 2.08 m (same as in section 3.1.1)
H - 17.38 m Applying Eq. (la): (X/Q) SWCB - 1.63x10 4 m-3 Applying Eq. (1b): (X/Q) SWCB - 5.22x10 4 m-3
i TXX-6116 Decemb:r 8, 1986 Page 10 of 16 The lower of the two X/Q's is the one calculated according to Eq.
(la).
Therefore, (X/Q) 1.63x10-4 m-3 is selected as the peak outside concentration.
3.2.2 Control Room Chlorine Concentration High Windspeed Case:
In order to select between Eq.
(3) and Eq.
(5), we test according to Eq. (4):
i a - 7.49 m at - 10 see Thus, 10/(0.64x7.49) - 2.09 > 1 Therefore, Eq. (3) is used:
R1 - 4.25x10-1 hr -1 (same as in section 3.1.2)
(Xo) SWCB - (1.63x10-4) x (2.268x10 ) - 36.97 g/m3 5
(X ) SWCB - 21.82 mg/m3 Applying Eq. (3):
1 4
Low Windspeed Case:
Eq. (7) is applicable:
R2 - 1.15x10-1 hr-1 (same as in section 3.1.2)
(X ) SWCB - 12.65 mg/m3 Applying Eq. (7):
2 t
i
TXX-6116 December 8,1986 Page 11 of 16 4.0 RESULTS The following concentrations of chlorine in the Control Room were obtained:
CR Chlorine Concentrations [in ag/m3(ppm)]
Release from Release from Circulating Water Service Water Case Chlorination Bida.
Chlorination Bldg; High Windspeeds 13.52 (4.51) 21.82 (7.27)
Low Windspeeds 7.84 (2.61) 12.65 (4.22)
TXX-6116 DecembGr 8,1986 Page 12 of 16
5.0 CONCLUSION
S The calculation of chlorine concentrations in the Control
- Room, following the guidelines of Appendix B
of NUREC/CR.3786, yields concentrations that are well within tho allowable limits of 45 mg/m3 (15 ppm) of chlorine in the Control Room.
In addition to the conservative assumptions listed in Appendix F of NUREG/CR 3786, a flat topographic profile was assumed in the calculation (i.e.,
the chlorine tank and the Control Room building are at the same elevation). The actual profile is illustrated in Figures 1, 2, and 3.
Therefore, since no credit is taken for the additional dispersion effect of the actual topographic
- profile, the calculated concentrations are conservative.
From the foregoing, we can conclude that the habitability of the CPSES Control Room is acceptable.
+
TXX-6116 Decemtor 8,1986 Page 13 of 16
6.0 REFERENCES
(a) TNE Calculation TNE-NU-CA 0000-484,
" Control Room Habitability Analysis for Chlorine Release," Rev. 1 (b) NUREG/CR-3786, "A
Review of Regulatory Requirements Governing Control Room Habitability Systems," August, 1986 (c) Comanche Peak Steam Electric Station, Final Safety Analysis Report, Figure 2.4-4 l
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TXX-6116 December 8, 1986
TXX-6116 CPSES/FSAR the operations phaso to contral major structural modifications till tt en 2 Page 1 of 5 comply with applicable guidance contained in Revision 1 (4/76) of this regulatory guide for activities which are similar to construction 8
activities. The application of the requirements of ANSI N45.2.5-1974, Q421.19 as endorsed by this regulatory guide, will be in accordance with the guidance provided in ANSI N18.7 - 1976.
Also refer to Section 17.2 Reculatory Guide 1.95 Protection of Nuclear Power Plant Control Room Operators Against an Accidental Chlorine Release Discussion The CPSES design complies with the intent of Revision 1 (1/77) of this 55 regulatory guide as described in Sections 2.2, 6.4 and 9.4.
A plant Q312.27 specific analysis has been performed in lieu of the isolated air exchange rate specified in Table 1 of this regulatory guide.
(See Rev.
Section 6.4.2.3)
Reculatory Guide 1.96 Design of Nain Steam Isolation Valve Leakage Control Systems for Boiling Water Reactor Nuclear Power Plants Discussion This regulatory guide is not applicable to the CPSES.
Reaulatory Guide 1.97 Instrumentation for Light-Water Cooled Nuclear Power Plants to Assess Plant Conditions During and Following an Accident 1A(B)-39
p TXX-6116 CPSES/FSAR December 8, 1986 Paga 2 of 5 is maintained by modulating exhaust dampers during normal plant
. operations and by emergency pressurization units during accident conditions. The boundaries of the Control Room envelope consist of concrete walls and floors which exhibit low leakage characteristics.
The overpressure of 0.125-in, wg is considered sufficient to prevent 21 infiltration. Table 6.4-4 lists potential leak paths and their appropriate leakage characteristics.
To minimize this leakage all joints and penetrations are sealed; all doors are gasketed and provided with metal interlocks.
Shutoff and isolation dampers are of the zero leakage type. All doors are-designed to swing inward except the missile resistant door which is airtight and opens outward. The maximum flow rate of the 3
pressurization unit for emergency operation is 800 ft / min which is sufficient to pressurize the Control Room envelope to 0.125-in, wg as 27 indicated in Table 6.4-4. However, leakage is expected to be less.
46 Periodic testing of the Control Room envelope is performed to verify this value and to ensure that adequate pressurization is maintained.
27 (See Subsection 6.4.5.) For an analysis of the dose received by Control Room occupants in the unlikely event of a LOCA, see Subsection 15.6.5.4.
The infiltration rate when the control room is isolated will be much Rev.
less than the exfiltraticn rate when pressurized to 0.125 inch water gauge since infiltration is due to wind loadings and much less than 55 half the leakage paths in Table 6.4-4 are exposed to wind loadings.
Q312.27 6.4.2.4 Interaction With Other Zones and Pressure Containina Eauioment The Control Room envelope is isolated and maintained pressurized during an accident involving the release of radioactive gases in surrounding zones.
The Control Room Air-Conditioning System is operated in the emergency recircu!ation mode, with outside filtered 6.4-7
TXX-6116 CFSES/FSAR December 8, 1986 Page 3 of 5 a site-related accident involving a release of hazardous chemicals exceeds the toxicity limits as specified in NRC Regulatory Guide 1.78.
Based on the analysis, acnitors are provided in the Control Room outside air intakes (a total of two per intake) of the Control Room 46 envelope to automatically switch to the isolation mode of operation.
Chlorine sensors are placed at the outside-air intakes which are approximately 600 feet from the nearest chlorination storage facility.
These automatically switch the Air-Conditioning System to the preferred mode of operation when chlorine levels unsafe for Control Room personnel (as suggested in NRC Regulatory Guide 1.95 [5] are detected. Chlorine is used as a biocide in the plant Circulating and Service Water systems. The Chlorination System is described in Subsection 10.4.5.
A plant specific analysis based on Reference 9 has been performed to demonstrate that the chlorine concentration in the control room would be we11 within the protective action limit of 15 ppm based on a maximum isolation air exchange rate of 800 cfm. The acceptance test Rev.
to verify the above isolation air exchange rate and the pressurization flow rate is that the Control Room can be maintained at greater than or equal to 0.125 in, wg with the measured pressurization flow rate less than or equal to 800 cfm.
6.4.4.3 Evaluation of Heatino. Ventilation. Air-Conditionina, and Filtration System The HVAC and Filtration System readiness is ensured by the periodic testing program described in Section 6.4.5.
Safe operation is ensured by having redundant equipment for the Control Room HVAC and Filtration System. A complete safety evaluation is given in Section 9.4.
6.4.5 TESTING AND INSPECTION Preoperational tests are conducted on the Control Room HVAC and Filtration System to ensure that all equipment satisfies the design criteria during all modes of operation.
Tests are also performed, as 6.4-11
TXX-6116 CPSES/FSAR December 8,1986' Att:chment 2 Pag; 4 of 5 9.
Jacobus, M. J., NUREG/CR-3786, A Review of Regulatory Requirements Governing Cct, trol Room Habitability Systems, Rev.
August 1984, i
i 6.4-15 9
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TXX-6116 CPSES/FSAR December 8 1986 TABLE 6.4-4 Page 5 of 5 POTENTIAL LEAK PATHS AND THEIR l
APPROPRIATE LEAKAGE CHARACTERISTICS
- Description g 3 min)
Comnonents of Comoonents
/
Pipe penetrations For all pipe Negligible penetration in the Control Room 55 Cable penetrations For all cable Negligible penetration in the Control Room Doors (assume hollow Total of twelve doors 703 (total) doors with metal (Ref. Figures 1.2-33, interlocking and 34,and36) gasket-seal weather strip)
Dampers CPX-VADPMU-05, 06 9 (total)
CPX-VADPOV-27, 28 All others Negligible Rev.
Tornado Blowout Panels Ten (10) panels 24 (total)
Leakage Due to Ingress All normal ingress and 10 Egress egress to stairwell and interior rooms which serve as the equivalent of i
vestibules.
I Unidentified Leakage Fan Margin 54 l
TOTAL 800 l
- The criteria used to establish leakages is based on a pressure differential of 1/4 in. wg. as specified in NRC Regulatory Guide 1.78(43 I
..